In several cases, the laws of war have been broken by both parties leading the war to be directed toward civilians, women, and children, or the use of mass destruction weapons against the military and civilians including chemical weapons, despite the use of which have been banned for decades under the Geneva Convention almost 100 years ago. After the war, the Chemical Convention has been established as a global convention with a control regime under the OPCW (Sydney 1972). Chemical war agents (CWAs) are strong chemicals that are used as mass destruction weapons. The chemical agents are used to kill, seriously injure, or disable people due to their physiological effects. The toxicity of these agents is because of their ability to interact with enzymes, proteins, and nucleic acids in living organs. The chemical agents are first cause stimulation in cells and then affect the cells as a cellular toxin in living tissues (Singha et al. 2016). Compounds such as sarin, soman, tabun, mustard gas, and lewisite are among the chemical warfare agents, which are also known as blistering, blood, nerve, asphyxiation, and riot control agents (Hellström and Ödalen 2013; Hanaoka 2005). Bis(2-chloroethyl) sulfide (sulfur mustard, mustard gas, also known as HD) is a blistering agent widely used during WWI, WWII, and also used during the Iran-Iraq conflict in the 1980s by the Iraqi army. Mustards can be divided into sulfur mustard and nitrogen mustard. As the injuries caused by mustard agents resemble those of burning and blisters, they are categorized as "blistering agents". Nonetheless, it is more suitable for those to be known as “blister and tissue destroying agents” as they cause severe eye, respiratory system injury, and internal organ failure. Also, because of the ability of mustard to covalently bind with a variety of biological molecules, the resultant biological damage could have considerably delayed consequences, and the first symptoms can occur between two to twenty-four hours after the exposure (Hellström et al. 2013). However, the mentioned issues are not the only destructive effects of sulfur mustard (Nilsson et al. 1992).
From the environmental point of view, most of the CWAs including mustard (HD) hydrolyze after solvation and produce degradable products such as thiodiglycol (TDG), 1,4-thioxane, 1,4-dithiane and 1,3-dithiolane. These compounds in aqueous media may act as a reliable proof of the original existence of HD. Moreover, some previous reports have been proven the persistence of these substances for up to 60 years (Tang and Keong Loke 2012). Therefore, these materials and their decomposition products are expected to exist in the environment and transferred from soil and water to plants and then to food chains, and finally to animals and humans. Thus, sensitive and precise determination methods for environmental and biomedical studies are required to verify the presence of sulfur mustard and its decomposition, oxidation and hydrolysis products (Tang and Keong Loke 2012; Deng and Evans 1997). However, despite the importance of this subject, the studies on the impact of chemical bombs onto the environment are very limited which can be due to the laboratory prohibition for working with CWAs or limited areas in the world in which these weapons have been used.
In this context, in 2005, Aldeen and Delaver studied the long term hazards of CWAs in the soil of Halabja in northern Iraq. Ten soil samples from contaminated areas and six samples from not contaminated areas were studied in this research. The presence of sulfur mustard or any other volatile agent in the samples was evaluated by Gas Chromatography-Mass Spectrometry (GC-MS) (Dlawer and Aldeen 2005).
In 2010, Toree et al. examined the environmental hazards of chemical weapons discharged into the South Adriatic Sea and demonstrated the effect of chemical gases on fish in the Mediterranean Sea (Torrea et al. 2010).
About the study area
The city of Sardasht with an area of 144.454 km2 is located in northwestern of Iran and near the border of Iraq (Fig. 1). The altitude of this city is 1840 meters above sea level and it has a population of about 50,000 people. The city has about 96 km of border with Iraq and is located in the south and southwest of the small Zab River Basin. Sardasht city has a mountainous climate and a Mediterranean rainfall regime (Khezri 2010). During the years of the Iraq and Iran conflict, the city of Sardasht was considered as a point of contact between the two parties, culminating in the chemical bombing, which is still taking its toll on the people after so many years. In July 1987, Saddam Hussein’s military had attacked the city of Sardasht with seven chemical bombs, four of which hit the city center and the other three land in a nearby valley inside Rashahrameh village.
It is the first city in which the weapons of mass destruction and chemical weapons have been used against its civilians after World War II. According to the letter of the Ministry of Foreign Affairs to the United Nations, at least 4600 peoples were killed or severely injured in that bombing. However, some resources were estimated this number to be about 7000 people (Ahmadi et al. 2010).
Considering that investigation onto the presence/absence or stability of these constituents in the environment and their possible threat to the health of residents thereby providing solutions for cleanup of contaminated areas is of great importance, the aim of this work was to investigate screening of chemical weapon compounds and their decomposition by-products in soil, water, and plants in the Sardasht region of Iran (Sanderson et al. 2012). Gas chromatography-mass spectrometry (GC-MS) as one of the most popular and powerful instrumental methods was used for qualitative analysis of chemical warfare residuals through the comparison of obtained mass spectral data with authoritative known and analogous compounds available in the library (Hanaoka 2005; D’Agostino and Hancock 2003).
To the best of our knowledge, there has been no research onto the existence of chemical weapon residuals in the Sardasht area of Iran so far.